System on a chip (SOC) implementation is predominantly based on design capture at the register-transfer level using design languages such as Verilog and VHDL, followed by logic synthesis of the captured design and placement and routing of the synthesized netlist in physical design. Current efforts to improve design productivity have aimed at design capture at a higher level of abstraction, via more algorithmic/system approaches such as C++, C, SystemC and System Verilog.
As process technology advances, physical design issues such as timing closure and power consumption management have dominated the design cycle time as much as design capture and verification. Methodology advances currently in development and under consideration for adoption using higher levels of abstraction in design capture do not address these physical design issues, and manufacturability issues. It is recognized in the semiconductor industry that with process technologies at 90 nm and below, physical design issues will have even more significant cost impacts in design cycle time and product quality.
CAD tools for placement and route of synthesized logic netlists have delivered limited success in addressing the physical design requirements of deep submicron process technologies. To take full advantage of deep submicron process technology, the semiconductor industry needs a design methodology and a supporting tool suite that can improve productivity through the entire design cycle, from design capture and verification through physical design, while guaranteeing product manufacturability at the same time. It is also well-known in the semiconductor industry that SOC implementations of stateful, transaction-oriented applications depend heavily on on-chip memory bandwidth and capacity for performance and power savings. Placement and routing of a large number of memory modules becomes another major bottleneck in SOC physical design.
Another important requirement for an advanced SOC design methodology for deep submicron process technology is to allow integration of on-chip memory with significant bandwidth and capacity without impacting product development schedule or product manufacturability. High level design capture, product manufacturability, and support for significant memory resources are also motivating factors in the development of processor-in-memory. Processor-in-memory architectures are driven by requirements to support advanced software programming concepts such as virtual memory, global memory, dynamic resource allocation, and dynamic load balancing. The hardware and software complexity and costs of these architectures are justified by the requirement to deliver good performance for a wide range of software applications. Due to these overheads, multiple processor-in-memory chips are required in any practical system to meet realistic performance and capacity requirements, as witnessed by the absence of any to system product development incorporating a single processor-in-memory chip package.
There is thus an added requirement for cost effective SOC applications that resource management in processor-in-memory architectures be completely controllable by the designer through program structuring and annotations, and compile-time analysis. It is also important to eliminate all cost and performance overheads in software and hardware complexity attributed to the support of hierarchical memory systems. Based on these observations, there is a need in the semiconductor industry for a cost-effective methodology to implementing SOCs for stateful, transaction-oriented applications.